It is correctly called Dehydration.
Head injury, as your head is your skull, damaging your skull is very serious as your brain is located there and damaging your brain could probably kill or limit some abilities
An individual's self-esteem can be affected by genetics as well as environmental factors, and poor self-esteem often begins in childhood. A person who experiences an abusive childhood or who didn't get enough approval from authority figures, feels his or her self-worth was based on achievements or feels excluded will often have poor self-esteem.
Continuing education is required and is available from a number of different sources
To focus I like to take a deep breath and look at who is talking.